The rotor of a turbine, especially of a gas turbine, can be built up from a number of discs. Each disc typically comprises a number of turbine blades which are attached to the periphery of the disc. A gas turbine blade usually comprises an airfoil, a blade root and a platform between the airfoil and the blade root. Between adjacent turbine blades which are secured to a rotor disc a root cavity occurs between root segments and platform segments.
To prevent the ingress of hot gases into the root cavity formed between neighbouring blade roots which can cause undesired heating of the disc rim, blade cooling air supply and seal strips are assembled between adjacent turbine blades. These seal strips are usually simple single plane elements and are retained via a notch in each of the adjacent turbine blades. The previously used designs for seal strips rely on tight tolerances; however this design bears the risk that some of the seal strips may fall out. Another design evolution tended to be tight axial. However, this evolution bears the risk of a locking of the platform. Both of these designs used axial restriction to retain the seal strip.
A seal slot misalignment from blade to blade may cause a subsequent locking of platforms due to the tilting of seal strips. Especially if the seal strip has a bent shape, any seal slot misalignment may magnify the tilt of the strip and may hence potentially cause platform locking.